The invention relates generally to agricultural vehicles and, more particularly, to systems and methods for cooling a diesel exhaust fluid (DEF) dosing module of an agricultural vehicle.
Emission regulations have lead engine manufacturers and aftermarket suppliers to install exhaust after treatment systems to meet the increasingly stringent requirements. Often, these systems direct exhaust gases through a series of reactions to reduce particulate matter and mono-nitrogen oxide (NOX) emissions in the exhaust stream. Moreover, because the treatment is done after combustion, existing equipment may be retro fit to include the exhaust after treatment systems.
Exhaust after treatment systems typically direct an exhaust stream toward a diesel oxidation catalyst (DOC). The DOC may contain a particulate filter to remove fines and other solid material from the exhaust stream. As the exhaust stream flows over the catalyst, an oxidation reaction may convert the hydrocarbons and carbon monoxide in the exhaust stream into carbon dioxide and water, among other compounds. Next, the exhaust stream may be directed toward a dosing module. The dosing module may contain an injection port for directing a DEF into the exhaust stream. The DEF may be a urea solution that decomposes into ammonia in the exhaust stream. Then, the exhaust stream may be directed toward a selective catalytic reduction reactor (SCR). In the SCR, the ammonia and some exhaust stream components may be converted to nitrogen and water. By using the exhaust after treatment system, emissions may be reduced to meet regulatory requirements.
While exhaust after treatment systems may reduce NOX emissions from diesel exhaust streams, manufacturers may have difficulties finding suitable locations to mount the additional equipment. This may be especially true in agricultural equipment where space under the hood is limited. Moreover, additional design constraints (e.g., temperature, pressure, etc.) may reduce the number of suitable locations for the exhaust after treatment system.
In some configurations, the exhaust after treatment system also utilizes support equipment. For example, the dosing module may use cooling at its injection port because of exhaust stream temperatures and/or to reduce crystallization of the DEF. Specifically, a cooling fluid from the engine cooling system may be used to cool the dosing module. However, because the cooling fluid flows from the engine cooling system when the engine is running (e.g., the engine supplies power to a pump), an additional reservoir may be used to store cooling fluid for cooling the dosing module after the engine is shut off. The additional reservoir may be plastic to reduce cost and weight, but may also use shielding to protect the plastic material from the heat of the engine and exhaust stream. Additionally, if the reservoir is mounted above the engine cooling fluid system, it may also have a vent to prevent vapor lock in the cooling lines. An extra vent in the system may lead to significant modifications to the engine cooling system. Furthermore, the reservoir may utilize an additional pump to enable circulation after the engine is turned off. However, because of the limited space under the hood, additional reservoirs, heat shielding, pumps, and vents may not be practical. Accordingly, there exists a need for a dosing module cooling system that can use cooling fluid from the engine cooling system without auxiliary equipment.